1. Field of the Invention
The present invention relates to communication networks and, more particularly, to Ethernet Operation Administration and Maintenance (OAM) domains and an Ethernet OAM frame format.
2. Description of the Related Art
Data communication networks may include various computers, servers, nodes, routers, switches, bridges, hubs, proxies, and other network devices coupled together and configured to pass data to one another. These devices will be referred to herein as “network elements.” Data is communicated through the data communication network by passing protocol data units, such as frames, packets, cells, or segments, between the network elements by utilizing one or more communication links. A particular protocol data unit may be handled by multiple network elements and cross multiple communication links as it travels between its source and its destination over the network.
The various network elements on the communication network communicate with each other using predefined sets of rules, referred to herein as protocols. Different protocols are used to govern different aspects of the communication, such as how signals should be formed for transmission between network elements, various aspects of what the protocol data units should look like, how packets should be handled or routed through the network by the network elements, and how information associated with routing information should be exchanged between the network elements.
Ethernet is a well known networking protocol that has been defined by the Institute of Electrical and Electronics Engineers (IEEE) as standard 802. Conventionally, Ethernet has been used to implement networks in enterprises such as businesses and campuses, and other technologies have been used to transport network traffic over longer distances. Specifically, network providers such as carriers were reluctant to deploy networks based on Ethernet technology, since Ethernet is designed to provide best efforts service and doesn't support Operation, Administration, and Maintenance (OAM) functions desired by the network providers. Since network providers need to be able to guarantee connectivity, Ethernet was felt to be inappropriate for deployment in these types of networks. When two Ethernet networks were to be connected over a network provider's network, the Ethernet frames would be converted to protocol data units using a transport protocol such as ATM, and carried over the network using the carrier's transport protocol. The Ethernet frames would then be recovered at the other side of the network provider's network and passed onto the second Ethernet network.
As the underlying networks have evolved and more and more Ethernet networks are being connected together, it has become more desirable to transport Ethernet frames in native form over the network provider's networks. Unfortunately, although it may be possible to overcome the limitations associated with the best-efforts nature of the Ethernet technology, other aspects of the Ethernet protocol still remain to be solved. For example, Ethernet does not enable certain Operation, Administration, and Maintenance (OAM) operations to take place to manage and diagnose problems on the network. This lack of OAM support in Ethernet prevents the network provider from taking measurements to perform fault detection, isolation, confirmation, and many other operations that a network provider or subscriber may wish to be able to do on the network. As Ethernet has expanded beyond a single domain, the ability to detect and isolate a network fault becomes more difficult rendering it necessary to implement OAM across Ethernet domain boundaries.